It is proposed to 1) study the effect of whole and fractionated embryo active oviduct fluid on embryo development to the trophoblast stage. Determine if any specific substance influences RNA or protein synthesis in the embryo, 2) Isolate estrogen modulated protein(s) from oviduct fluid and biochemicallycharacterize the protein(s) and study its effect on embryo culture and RNA and protein synthesis, 3) Determine if oviduct fluid contains lytic factors which will help remove decapacitation factor(s) from sperm or enhance capacitation. BIBLIOGRAPHIC REFERENCES: McLaughlin, K.C. and Hamner, C.E. Preliminary Characterization of Rabbit Oviduct Fluid Trypsin Inhibitors. Biol. Reprod. 12, 556-565, 1975. Lambert, R.D. and Hamner, C.E. In vitro Fertilization of Rabbit Eggs in Oviduct Secretions from Different Days Before and After Ovulation. Fertil. Steril. 26, 660-664, 1975.